WARNING: The following article contains spoilers for Captain Marvel, in theaters now.
Kevin Feige and others at Marvel have been open about how Captain Marvel (Brie Larson) is arguably the strongest hero in the Marvel Universe. She's been billed as one of the few people who could maybe go head to head with Thanos, leaving fans to wonder just how she becomes powerful enough to step up to someone who easily beat down the Hulk.
The events of Captain Marvel both reveal how she got her powers and why they make her so strong. Her origin also proves that Carol genuinely stands apart from the rest of the heroes of the Marvel Cinematic Universe, and that she is capable of something that no one else in the universe has been able to accomplish.
Flying alongside Talos (Ben Mendelsohn), Nick Fury (Samuel L. Jackson) and Maria Rambeau (Lashana Lynch), Danvers visits the space station that served as Mar-Vell's (Annette Bening) old lab, which is still flying around cloaked and in Earth's orbit. There, they discover the power source that Mar-Vell was experimenting with. The source is revealed to be the Tesseract, discovered in the years since it sank to the bottom of the ocean alongside Captain America. It was the energies from the cube that fueled the experimental engine Mar-Vell constructed on Earth. Carol was exposed to those same energies when she destroyed the engines like Mar-Vell instructed, which fused with her body and empowered her.
We now know the Tesseract was actually the Space Stone, one of the six Infinity Stones and a potent tool for anyone who could get their hands on it. In the end, Captain Marvel manages to get the Tesseract onto Earth and back into Fury's possession. This means that Carol got her powers directly from an Infinity Stone and was empowered by it instead of being overwhelmed. Which, taking previous MCU films into account, is a pretty big deal.
It explains just how strong Carol is, and how she can destroy entire Kree flagships with relative ease. This revelation elevates the importance of Carol Danvers within the MCU to a cosmic scale. Other heroes have used Infinity Stones, of course, but none of them got the kind of power boost that Captain Marvel received.
Doctor Strange didn't get a permanent upgrade from the Time Stone, he just knows how to use it effectively. Star-Lord was only able to withstand the power from the Power Stone because of his hybrid biology (being both human and the son of Ego, a Celestial) and even then it took the rest of the Guardians sharing their lifeforce to get it under control briefly. Vision was empowered by an Infinity Stone, but that proved to be the thing keeping him alive. By contrast, Carol adapted to the powers of the Space Stone with just her own body, making her one of the strongest singular forces in the MCU without actually needing the stone in her possession.
This will likely make Captain Marvel vital in the coming battles with Thanos, giving her the chance to stand up to the Mad Titan. The after-credits sequence of Captain Marvel reveals that Carol returns to Earth after the events of Infinity War, confirming that she'll be working with the Avengers to restore the universe. This gives her the potential power to stand toe to toe with Thanos, which the heroes desperately need.
It also means that the heroes of the MCU have an all-new power player who could easily assume a leadership role if and when such a position were to become vacant. Many fans are expecting at least some heroes like Captain America and Iron Man to fall by the end of Endgame, and Captain Marvel makes it very clear that Carol Danvers has more than enough power to take over their roles as one of the chief defenders of Earth.
Directed by Anna Boden and Ryan Fleck from a script they wrote with Liz Flahive, Carly Mensch, Meg LeFauve, Nicole Perlman and Geneva Robertson-Dworet, Captain Marvel stars Brie Larson as Carol Danvers, Samuel L. Jackson as Nick Fury, Jude Law as the commander of Starforce, Clark Gregg as Phil Coulson, Lee Pace as Ronan the Accuser, Djimon Hounsou as Korath the Pursuer, Gemma Chan as Minn-Erva, Ben Mendelsohn as Talos, Lashana Lynch as Maria Rambeau, Algenis Perez Soto as Att-Lass, McKenna Grace as a young Carol Danvers and Annette Bening as Mar-Vell/the Supreme Intelligence.